Article stacking apparatus



y 5, 1953 A. 1. ESHELMAN 2,637,450

ARTICLE STACKING APPARATUS Filed Oct. 14, 1949 4 Sheets-Sheet l N E E T SHELMAN 141. w L NH 2 Z INVENTOR.

A. L. ESHELMAN ARTICLE STACKING APPARATUS May 5, 1953 4 Sheets-Sheet 2 Filed Oct. 14, 1949 .441. V/N law/E27.- El/EL MAN,

' INVENTOR.

BY W May 5, 1953 A. L. ESHELMAN 2,637,450

ARTICLE STACKING APPARATUS Filed Oct. 14, 1949 4 Sheets-Sheet 5 41v ALVIN LENHEQ ES'Z y 5, 1953 A. L. ESHELMAN 2,637,450

ARTICLE STACKING APPARATUS Filed Oct 14, 1949 4 Sheets-Sheet 4 OVERHEAD Pusmzrz CONVEYOR spseo Cunms A1. VIN .ZE'NHEET EEHELMA IN VEN TOR.

Patented May 5, 1953 UNITED STATES PATENT OFFICE ARTICLE STACKING APPARATUS Alvin Lenhert Eshelman, Upland, Calif.

Application October 14, 1949, Serial No. 121,242

8 Claims. 1

This invention relates to article stacking al paratus. More particularly it relates to app tus designed for receiving a series of articles, such as boxes, which are advanced in single file, and for positioning them, one upon another, to form a vertical stack of a desired number of boxes.

The invention has particular practical application in the handling and storing of boxes, lugs or crates in which fruit or vegetables, for example, are commonly contained incidental to the various processing operations which such commodities may undergo in a packing house preparatory to shipment to market. Numerous types of box stackers, as apparatus of the type disclosed herein is generally called, have been devised and have received wide acceptance in the fruit and vegetable packing industry. The purpose, of course, of thus stacking the boxes is to conserve floor space in the packinghouse and the mechanical stackers permit the stacking of the boxes to a greater height than could conveniently be done by hand, stacks as high or higher than ten feet being quite common.

In many of the prior stackers the boxes to be stacked are fed into the stacker at floor level and are lifted by the stacker to build up, from below, a tier of the desired number of boxes. Such stackers, however, unavoidably use up a large amount of floor space in the packing house, because of the necessity of floor feed conveyors of some form, which space could otherwise be put to use for other processing equipment or for storage. In another form. boxes are fed into the stacker from considerably above floor level by elevated or overhead conveyer means and the boxes ar then lowered, one upon the other, by the stacker to develop a tier of the boxes.

It is with this second type of stacker that the present invention is more especially concerned and it is a purpose to provide a stacker which is mechanically simple and more efficient than previous ones of the generally related type. One of the chief advantages or the stacker here disclosed is that it is well adapted to receive boxes fed to it by overhead conveyers in a packing house, thus permitting the space below such con veyers to be used for other purposes. This arrangement is especially desirable in lemon packing houses, for example. In preparing lemons for shipment to market, the general practice employed by the packing house operators is to wash the lemons as they are received from the field, after which they are sorted according to color. Several distinct color grades of lemons are recognized by the trade and only those of a particular color are shipped to market. Normally many of the lemons as picked are quite green and are not suited for immediate shipment but must first be stored under particular temperature conditions and frequently in special atmospheres to bring out the desired color. Customarily, therefore, the lemons, after being washed, are spread out on grading tables where operators select them according to color and place them in wooden boxes so that each box contains lemons of only one color grade. All the boxes are then placed upon conveyers which carry them to the stackers. In a typical system employed in many of the packing houses, the number of stackers employed is equivalent to the number of color grades into which the lemons are divided, and as a box of a particular color grade of lemon is advanced by a conveyor, means are provided for diverting that box to a particular stacking unit so that the stack formed by that stacker will consist of boxes of lemons of the same color grade. Similarly boxes containing lemons of a dilTerent color grade will be diverted from the main conveyer to different stacking units and will be collected at respective points. The stacks formed at each of the respective stacking units are then collected and sent to storage, all of the boxes of one color grade being stored together and separated from those of other color grades. The lemons then remain in storage varying lengths of time, depending upon their initial color grade, until they acquire a color which is deemed desirable for shipment to market. Since in some instances, storage periods of a considerable length of time are required, it is apparent that a large amount of storage space is often required. The provision of astacking system, therefore, which is adapted to be hung overhead in a packing house is especially advantageous for lemon packing operations. For example, this arrangement permits the stacking system to be placed above the wash room equipment, thus making use of space which would not otherwise be occupied.

In furtherance of this same purpose the stacking mechanism of the invention also incorporates a box releasing or stacking mechanism which is of extremelysimple construction and which permits further conservation of space in the packing house.

, Other objects and improvements provided by the stacker disclosed herein will become apparent from the description of a typical practical unit illustrated in the following drawings in which Fig. 1 is a view in side elevation of a typical stacking unit;

Fig. 2 is a view in perspective showin in greater detail certain parts illustrated in Fig. 1;

Fig. 3 is a partial view in side elevation of box trap actuating means;

Fig. 4 is a partial view in and elevation of parts shown in Fig. 3;

Figs. 5 and 6 are enlarged fragmentary views showing details of the box trap mechanism in different positions;

Figs. '7' and 8 arediagrammatic; views: of box stop mechanisms used in controllingthe. delivery of boxes to the stacker;

Figs. 9 and 10 are diagrammatic views showing: in greater detail portions of box feeding. mechanism; and

Fig. 11 is a schematic of the electrical controL circuit for the stacking mechanism.

The typical stacker installat on illustrated in Figs. 1 and 2 is of the type, mentioned above,) which is particularly adapted to be placed above other processing, apparatus in the packinghouse,

although it will be obvious that it may also be placed directly upon the floor of the packing house if so desired. The stacking unit, regardless of the particular manner in which iti's supported, comprises, generally, conveyer means and accompanyingj supporting framework which define a runway R along which individual boxesB' of fruit are advanced. seri'ati'm to the head ortop of a stackingv station S at the end. of runway R. At

this. point,. boxes B rest upon retractable roller I supports which,v when withdrawn from their boxsupporti'ng position, deposit the box upon a stack forming elevator E directly beneath station S; Elevator E" moves down with the delivery of each box so as to make room for a succeeding box until avertical stack of a desired number of'boxes has been. formed in the elevator. Thereafter, the stacl': is lowered by the elevator to a point of" delivery; such as the floor level of a storage room, where the stack is. then removed from the elevator by a powered conveyer which is pushed. beneath the stack into. the box passageway of the elevator.

The sup orting. frame upon which various elements of. the stacker unit are mounted comprises a pair of spaced, horizontal channel. members l5 forming. the sides of" runway R, and cross braces [5" extending transversely between and secured to these channels. Vertical leg members l1, l8 and T9 are also. provided wh ch support the unit above the mounting platform upon which. the present un t is designed to. rest.

Boxesfilled with fruit are delivered by a conventional'. convever C to a short transfer conveyor at the rear or start of box runway R: i. e., to the left in Figs. 1' and 2. Conveyer 20 consists in instance of a pair of endless chains 9| constra ned for travel bet een paired sprockets 2'2 and. 23' adjacent opposite sides of the box run, the up er runs of chains 2| se v ng to support and advance the box or boxes resting u on them. Sprockets 2'2 are carried. u on a. transverse sha' 't 24 which. is supported in. bearings (not here shown) mounted on. frame members; Snrockets 23' are ke ed to a dri ing shaft 25 ournaled in bearings 25 on channel rrem ers l5. Boxes delivered by conveyor (3 are. advanced in seouence by chains 2| from left to right (Figs. I and 2) towards stack ng station S at the opposite end of the. runway. Ad'vancer ent of each box in turn and in timed relation with the. preceding box is eifected by cooperating. box stop controls 28' and 39 located .iust prior, in point of t avel of the boxes, to station S, and by an overhead pusher conveyer 3U. Conveyor 20 operates continuously vancing box.

to advance boxes toward the stacking station and driving power for this conveyor is obtained from motor 3| through a chain and sprocket connection. This connection comprises a sprocket 32 keyed to motor shaft 33, a chain 34 driving sprocket 35, the latter being keyed to shaft 36 to which a sprocket 31 is also made fast. A chain 38 passes around sprocket 3'! to a second sprocket 39, the latter sprocket being journaled in bearings (not; shown) adjacent driving: shaft 25- of conveyer 20. A sprocket 40 keyed to shaft 25 engages roller chain 38 intermediate its travel between sprockets 3'! and 39 to transmit power to when chains 2|. The driving connection be- I tween-motor. 3|: and conveyer 2o just-described is arranged to effect a linear speed of chains 2| which is substantially higher than that of conveyer C feeding transfer conveyer 20, so that boxes on conveyer 0, even though in end-to-end abutment, will. be spaced apart on conveyor 20 by the momentary acceleration imparted to them by" chains 2|.

In order to correlate the various stacking, operations, boxes 13' must be fed to station S. in properly timed-i seouence. To this end a box advancing on conveyer 20 first encounters an upstanding bar 4| of box stop 28.. As. shown diagrammatically in Fig. 7, bar 4| is pivotally mounted upon a pin 42' which is journal'ed in opposite sides of housing 43 enclosing the stop mechanism. Bar 41 issoring biased so as to be normally retained in upstanding position against an abutment 4 4'. thereby causing it to project between chains 2| and into the path of an ad- Stoo 28 also includes a trigger member 45 supported within housing; 43 u on a pin, 6'6 passing througliv an elongated slot inv the trigger to' provide a lost motion connection. Trig er 45' has secured to it a rearwardl'y slanting contact shoe 41' which projects through. the rear of housing 43 and into the path of the overhead boxes. A compression spring 48' positioned. between trigger 45 and housing 43' causes the trigger to be pivoted in a counterclockwise manher about pin; 46 against a stop 49 whenever there is no box in contact with shoe 4]. Trigger 45 is also provided on its upper face with a substantially vertir'ally-faced projection 50. Bar 4|, in turn, is provided at its lower end. with a projecting tooth. 5|. which. whenever shoe 4! is depressed by a previously advanced box, is engaged by pro ection 50 so as to prevent the clockwise pivotal movement of bar 4| about pin 42'. In: this latter condition, therefore, bar 4| acts as a. positive sto for an. advancing box and causes the box to be retained at that point; Chains 21 of transfer conveyor 20 then merely skid beneath the box supported by them. When, ho ever, there is no box resting uoon shoe 41, tri ger 45 is permitted to pivot against stop 49, in which position it no longer engages stop bar. 41,. and the latter may be swung forwardly and downwardly against its spring bias out of theway of the advancing, box to allow the box to pass freely thereover.

Uoon passing; stop 28, a box continues. to ride upon endless chains 2| of transfer conveyor 20 until a portion of the box passes off the forward end of this. conveyer ('i. e. to the right in Figs. 1, and 2) and rests upon. a series of idler rolls 5! which are suitably journaled in bearings, not shown, secured to frame members l5. At this. point the advancing box en ages the second stop member 28,, in which position the box isv then. partially supported upon the forward end of con-v veyer 20 as well as upon idler rolls 52. The operation of stop 29 is diagrammatically illustrated in greater detail in Fig. 8, from which it will be seen that the stop is mounted between sections 52a of a split idler roller upon a shaft 53 also journaled for rotation transversely of frame members l5, whereby the stop may be caused to project into and to be rotated out of the path of boxes advancing along the runway. Here again, stop 29 is normally urged by spring means into a position in which it projects into the path of the boxes. Shaft 53 to which stop bar 29 is secured is provided with a ratchet 54 having a tooth 55 normally engaged by a pawl 56. urged intoengagement with tooth 55 of ratchet 54 by a compression spring 58. In such position bar 29 is thus restrained from clockwise rotation and prevents the advance of a box resting against it. This again causes chains 2| to skid beneath that portion of the box still resting thereon. By means presently to be described pawl 56 is depressed at the proper time to release ratchet 54, thus permitting stop 29 to be rotated against its spring bias and out of the way by the advancing box. Upon passage of that box, stop 29 is-immediately free to be returned to its projecting position by its spring. Stop means are also provided for preventing counterclockwise rotation of stop 29 beyond its upright position.

From a position adjacent stop 29, a box is next advanced, when the stop is withdrawn, to stacking station S at which point it comes to rest against a stop 59 disposed across the end of run-- way R. In thus advancing to station S, the box passes over an idler roll 68 loosely journaled upon shaft 6| whichlatter is carried in bearings 62 on frame members IS. The box is transferred from roller 50 onto two rows of s ate wheels 63 which are positioned along opposite sides of the box runway at station S. Skate wheels 63 are mounted upon horizontally projecting arms 64 each having a vertical stub shaft 64a journaled at opposite sides of the station in bearings 65 on the webs of channels I5. Arms 54 in each series, four in the example here illustrated, are connected together by a tie-bar 66 by which they are adapted to be pivoted simultaneously in a horizontal plane from a position in which the arms project inwardly towards each othersubstantially perpendicular to channel members l5, in which'position skate wheels 83 are spaced apart a distance less than the width of a box so that the box may be supported thereon, and a retracted position in which the arms lie substantially adjacent the respective longitudinal members I5, in which position the skate wheels of opposite sets are spaced apart a distance greater than the width of a box and are thus incapable of supporting the box while in such position. Boxes are delivered one at a time to station S while arms 54 are in their extended position as shown in Fig. 5. Thereafter arms 64 are swung horizontally to the position shown in Fig. 6 so as to withdraw skate Wheels 53 by rolling them arcuately from beneath the box, whereupon the box is released and; drops vertically.

As mentioned previously, movement of a box to its position against stop 59 at station S is initiated by the fact that therear of the box is still resting upon speed chains 2|. .Thereafter the advance of such box is accomplished by means of overheadconveyer 30 which comprises a set of parallel, spaced endless chains Bleach U 'disposed for travel between a sprocket 68 secured Pawl 56 is pivoted upon a pin 51 andis' 6 to shaft 69 at the rear and a sprocket IO-jounnaled upon a shaft H at the front of thereonveyer. Shafts 69 and II are each carried in bearings supported from uprights l1 and 12, respectively. Conveyer 30 is driven by a motor I3 through a chain and sprocket connection consisting of a sprocket 14 keyed to the shaft of motor 13, an endless chain 15 and a sprocket 16 keyed to shaft 69. One of the endless chains 61 is provided with a horizontally projecting-lug 11. Upon actuation of conveyer 30 from a'predetermined starting position to which it'is'arranged to return as described hereinafter, this 111g contacts a rocker l8- Rocker 18 is pivoted upon a pin 19 mounted in a suitable frame member adjacent the lower run of chain 61." The rocker is also connected to pawl 56 of stop 29 by a push rod (Fig. 8) so that contact of lug 11 against rocker 18 serves to depress pawl 56 thus permitting stop 29 to rotate out of. the path of a box resting against it. With further movement of chains 6'! a box-engaging bracket 8|, pivotally suspended upon an extended roller pin 82 passing between oppositely disposed roller links of chains 51, comes into contact with the upper rear edge of a box and thereafter pushes that box with advance of conveyercha ins'fl so as to move the box into position against stop 59 at station S. In the box-engaging position of bracket 8| as shown in Fig. 9, the bracket is prevented from clockwise pivotal movement about pin 82 by engagement of a roller 83 mounted upon its trailing leg 8 la with the underside of a track suspended between and extending substantially the full length of the lower run of chains- 61. Thus, the bracket is enabled to exert a forward thrust to a box during the time that roller 83 remains in contact with track 84. Track terminates just short of the forward end of conveyer 30 so that when roller 83 passes beyond this point the bracket is no longer prevented from rotational movement" about pin 82 and accordingly pivots backwardly-allowing it to pass over the upper edge of the box with which it is then in contact. The terminal point of track 84 is designed to permit the release of bracket 8| at the point in the latters travel where the box comes up against stop 59 at station S. During further travel of bracket 8| around shaft H and throughout its return run, it merely swings freely about its pivot to prevent interference with other parts of the stack ing mechanism. Upon delivery "of a box to station S in the manner just described, actuation of arms 64 to withdraw the supporting skate wheels is a'cf- '88 having a hub 89 is secured by key or set screw engagementwith the shaft within hub .89, An upstanding post 90 is secured to the outer end of crank arm 88, and the crank is so mounted on its shaft as to cause post 90 to bev engaged by the extended roller chain pin 82 of conveyer 30 during thefinal portion ,of the lower runof chains 61. Shaft isalsoprovidedwitha'sec and crank arm 9! having a collar 92 securing the crank arm to the lower end of the shaft by set-screw or key means. A link 93 pivotally connect's the outer end of crank 9| to tie-bar 96 and as post 90 is contacted by extended chain pin -92 during travel of the latter, shaft 85 is turned, withthe result that skate wheels 63 are arcuate- 1y withdrawn from beneath the box then resting thereon. The position of shaft 95 coincides approximately with the forward end of overhead conveyer 30, and the horizontal travel of extended link 82 while in contact with post 90 is accordingly of only short duration since pin 02 in passing upwardly around sprockets I at the forward end of conveyer 30 slides off of the post and the mechanism is thereafter free to return to its original position. Such return is accomplished by means of an extension spring 94 connected between the-forward end of tie-bar 66 and an upright member 95 of the supporting frame, the spring being put under tension whenever the skate wheels are swung out of their box supporting position.

- A box, upon release at station S by actuation of the trap mechanism just described, drops vertically a short distance until coming in contact with a pair of oppositely disposed supporting brackets 96 and 91 carried by stack elevator E. Since the supporting skate wheels 63 are withdrawn from beneath the overlying box by movement in a horizontal arc, the distance which such box must fall need not substantially exceed the diameter of skate wheels 69. This reduces the shock imparted to the boxes in stacking them and it also serves to reduce the overall height of the stacking mechanism. Elevator E is composed of opposed pairs of'endless chains 98 and 99, chains 98 being disposed for travel about sprockets I00 on shaft 0| at the head of the elevator and sprockets IN on shaft I02 at the foot thereof. Chains 99, in turn, are disposed to travel between sprockets I03 on shaft I04 at the head of the elevator and sprockets I05 on shaft I06 at the foot. Brackets 96 are carried between chains 98 while brackets 91 are carried between chains 99, movement of chains 99 and 99 being so coordinated as to maintain brackets 96 and 91 horizontally opposite each other throughout the adjacent runs of chains 98 and 99, respectively. .In order to accomplish this, a sprocket II" is keyed to the outer end of shaft GI and a sprocket I08 .is similarly keyed to the outer end of shaft I04. Sprockets I01 and I08 are-connected together for simultaneous movement by an endless chain I09. A driving motor I I0 mounted on the frame supplies power through a sprocket III to chain I09. Moving in a counterclockwise direction from a starting point on sprocket II I, chain I09 passes around sprocket I08 from below, over the top of this sprocket to an idler sprocket II2 mounted on a shaft II3 journaled on upright I2, and down around the lower right-hand periphery of sprocket I01 to return to driving sprocket III. In this manner sprockets I01 and I08 are caused to rotate mutually so that chains 99 and 99 in their adjacent runs move downwardly at the same relative speed. At the start of the stack forming operation, a set of brackets 96, 91, is adapted to be positioned just below the level of skate wheels 63 so that upon withdrawal of the latter, the box resting thereon is dropped upon the brackets. Elevator E moves brackets 96, 91, downwardly a distance corresponding to the height of a box. and the succeeding box, when released by the trap mechanism,'drops into position upon the upper edge of the first box and the elevator is again lowered. This operation continues until the desired number of boxes has been accumulated in a stack, whereupon the elevator then lowers the stack to the level at which such stack is to be removed. In apparatus of the present type, the stacks when formed may be removed at a series of difierent levels since elevator chains 98 and 99 may pass downwardly through a shaftway extending through several floors in the packing house. In such an arrangement, therefore, a section of conveyor may be slid into position at any floor level so as to lie between brackets 96 and 91 and to receive a stack carried by such brackets and remove it laterally from between chains 98 and 99. At the lowest level, of course, permanent conveyor means may be installed to remove stacks, such means comprising reversible floor chains H4 in the present instance. -With continued travel of conveyer chains 98 and 99, brackets 96 and 9! pass downwardly and then outwardly around sprockets WI and I05 respectively to return to their initial positions at the head of the stacker.

Synchronization of the various steps of operation from the delivery of individual boxes to the removal of completed stacks is accomplished by means of a system of electrical controls for driving motors 3I, I3 and H0 as follows: Assuming a starting condition in which no boxes are present at any point in the stacking unit, motor 3! runs continuously to drive speed chains 2| of'conveyer 20 and for this purpose electrical power is supplied directly from power mains I20 and I2I whenever the main power switch I22 is closed. Upon delivery of a box by conveyer C to speed chains 2 I, such box is then progressed along the runway through stop 28, as previously described, until'it comes to a halt against stop 29. At this point the box contacts a roller I23 which actuates switch I24 to move the switch from its normally open position into a circuitclosing position. Closing of switch I24 serves to complete the circuit to motor I3 for overhead conveyor 30 from power main I2I through points I25 of switch I26 (located on upright 95 at the forward end of station S) and through points "I27 of a magnetic controller I26. Switch points I25 are spring biased to a normally closed position but are adapted to be opened by contact of a box against a switch operating arm I39 pivoted to upright 95 at the end of the runway. A parallel'circuit to motor I! bypassing switches I24 and I25 is also provided through a switch I29 located above sprockets 10 of conveyer 30. Switch I29 is adapted to be actuated by contact of bracket BI in passing between the sprockets.

' The points of this switch are normally closed but at the starting position above assumed they are held open by contact of bracket 8| with the switch-actuating arm. Upon completion of the circuit to motor I3 through the first-named path, overhead conveyor 30 begins to operate. Initial movement of this conveyor causes bracket 8| to move out from under switch I29, allowing the latter to close, thus bypassing a portion of the initial circuit to motor I3. Further travel of conveyer causes lug "IT to contact rocket I8 effecting release of stop 29 in the manner described hereinabove. Immediately thereafter, pusher bracket 8I comes into contact with the rear upper edge of the box and pushes the box over idler rollers 52, 52a, 80, and then onto skate wheels 63. Arrival of a box at station S causes switch I26 to be moved into its alternate position by contact of the box with arm I39. Such action then opens contacts I25, but the circuit to scribed. At this point brackets 96 and 91 of elevator E have been brought into position just below the skate wheels for reception of the box released thereby and the elevator continues to lower the box deposited thereon until the upper edge of the box passes beneath the lower end of switch arm I39. I26 returns to its original. position, opening contact points I30 and closing contact points I25. With the opening of contact points I30, operation of the elevator is interrupted. Meanwhile bracket 8| again comes in contact with the opcrating arm of switch I 29, whereupon overhead conveyer 30 ceases operation; that is, provided there is then no box depressing switch I 2 3 adjacent stop 29. Where a succeeding box has arrived at switch I24, conveyer 30 of course continues operation without interruption.

In any event, when the next box in the series is delivered by'speed chains 2I, switch I24 is again closed and the same sequence of operations is repeated. With delivery of successive boxes, elevator E continues to move downwardly as the stack is formed. In order to limit the number of boxes in a stack, a contact lug I3I is positioned on chain 99 and is adapted to come in contact with the operating arm of a switch I32 when the top box in the'stack has been delivered. Switch I32 completes a circuit from power main I through the operating solenoid I33 of magnetic controller I28. Thereupon switch contacts I2! are opened while contacts I34 and I35 are closed. Closing of contacts I34 completes an alternate or holding circuit for solenoid I33 so that even after lug I 3| has passed beyond switch I32 and the latter has returned to its normally open position, the magnetic controller will be held in its last-mentioned position. In this position, the circuit to motor I3 for overhead conveyer is broken at contact points I21.

At the same time an alternate circuit to elevator motor III) is completed by contact points I so that the elevator continues to move downwardly even after the top box has passed below operating arm I39 of switch I26. The holding circuit for magnetic controller I23 also includes a normally closed switch I36 which is in series with contact points I34. Switch I36 is positioned adjacent the outer or return run of el'evator chains 99 and one of the latter is pro vided with a projecting lug I31 secured there to. As the bottom of the stackcarried upon brackets 96 and 9! is deposited upon floor chains II4'.'(or reaches such other level at which the stack is to be discharged) this lug contacts the operating arm of switch I36 thus interrupting the circuit to solenoid I33 of the magnetic con troller, and the armature of the controller is returned by spring action to its first position. This breaks the circuit through points I35 of the controller and'stops the downward travel of elevator E. No boxes, of course, can be delivered to station S during this last mentioned cycle of Conveyer 39 is meanwhile still in When this occurs, switch operation since the circuit to the driving motor for overhead conveyer 30 has been interrupted by opening of contact points I27 and the boxes are then held up by stops 28 and 29. However, upon return of the magnetic controller to its initial position, the normal cycle of operations above described can then take place again. Meanwhile floor chains II4 are actuated to remove the stack thus deposited upon them from between elevator chains 98 and 99, from which point the stack is then transferred to the coloring rooms or other point of storage.

It will be apparent that the relative positioning of switch I32 along the return run of elevator chains 99 will determine the number of boxes in a stack formed at station S, and that the desired number of boxes in a stack may therefore be readily controlled by proper placement of this switch. Similarly the level at which the stacks are removed. from the elevator can be controlled by the positioning of switch I36. In some instances also, the operating lugs for switches I32 and I36 may be an additional set or sets of box supporting brackets carried by the elevator chains.

Modifications of the specific apparatus here illustrated will be apparent to those skilled in the art and the invention is accordingly not limited to the specific illustration here given.

What is claimed is:

1. In an apparatus for stacking articles which includes an elevator, an article delivery station at the head of said elevator including trap mechanism for receiving an article and releasing it onto said elevator to form a stack of superimposed articles, and feed conveyor means including an overhead conveyor for advancing articles seriatim into said station: the improved trap mechanism which comprises members mounted at opposite sides of said station and adapted and arranged for horizontal pivotal movement about vertical axes between an extended position in which they project inwardly from opposite sides of said station, in which position they are capable of supporting an article delivered to said station, and a retracted position disposed closely adjacent the sides of said station, in which position they are incapable of supporting such article; an article stop in front of said station, said stop being biased so as normally to project into the path of articles advancing on said feed conveyor, means for supporting said stop for rotational movement whereby it may be rotated out of the path of advancing articles by such articles themselves, ratchet and pawl mechanism associated with said stop supporting means for engaging the latter and holding it against rotation, spring means urging said pawl against said ratchet to retain said box stop in article-intercepting position, an arm pivotally connected at one of its ends to said pawl, a rocker disposed in the path of said overhead conveyor to which the opposite end of said arm is connected, and a member carried by said overhead conveyor for contacting said rocker to effect release of said ratchet whereby said box stop is permitted to be rotated out of the path of an advancing box.

2. In an apparatus for stacking articles which includes an elevator, an article delivery station at the head of said elevator including trap mechanism for receiving an article and releasing it onto said elevator to form a stack of superimposed articles, and feed conveyor means for advancing articles into said station, the combination of: a trap means including members pivotally mounted at opposite sides of said. station for movement in.

a horizontal plane into and out of article sup porting position; spring means ope-reply connected to said members for normally biasing said members into article supporting position; lever means connected to said members and adapted to be actuated by said feed conveyor means for retracting said members out of article supporting position; and means for feeding said articles in spaced relation into said station and. including stop means pivotally mounted in front of said station and normally biased into article Stop position; means operably connected to said stop means for releasably holding said stop means in said stop position, said releasable means including a member extending into proximity With said feed conveyor means; and an element carried by said conveyor means adapted to contact said last mentioned member for releasing said stop means.

3. In an apparatus for stacking articles including an elevator, an article delivery station at the head of the elevator, and means for delivering articles to said station including a conveyor, the combination of a trap means Within said station comprising opposed sets of inwardly extending horizontal members; anti-friction means carried on said members for supporting engagement with articles to be stacked; said members being pivoted about vertical axes for movement in a horizontal plane into and out of article holding position; spring means biasing said members into article holding position; lever means connected to said members; and means carried by said lever means for cooperable engagement with said conveyor for moving said members out of article holding position.

l. A trap mechanism for an article receiving station disposed at the head of an elevator stacking means and -a conveyor means comprising: roller means pivotally mounted for movement in a horizontal plane at opposite sides of said station and normally spring biased into trap closing position for supporting an article; and means for retracting said roller means simultaneously into trap open relation for releasing an article into the elevator stacking means; said retracting means at each side of said station including a lever means connected to said roller means, a crank means operably connected to said lever means, and means carried by said crank means adapted to be intermittently contacted by said conveyor means for retraction of said roller 5. In an apparatus for stacking articles including an elevator and an article delivery station at the head of the elevator, the provision of: feed conveyor means for advancing articles in predetermined spaced relation into said station comprising a driven transfer conveyor portion, an idle conveyor portion between the transfer portion and the station, and an overhead conveyor portion above said transfer and idle portions and said station; a first article stop means positioned in the transfer conveyor portion and including a member to be engaged by an article which has passed said stop means to maintain said stop means in article stop position; a second stop means positioned in the idle conveyor por-- tion and normally spring-biased into stop position; said member of the first stop means being released upon advancement of an article from between said first and second stop means; release means for said second stop means including a member on said overhead conveyor portion adapted to actuate said second stop means into released position; trap members at said delivery station normally spring-biased into trap veyor portion engageable with said lever means for actuating said trap members into trap release position.

6. In an apparatus for stacking articles including an elevator and an article delivery station at the head of the elevator the provision of: feed conveyor means for advancing articles in predetermined spaced relation into said station comprising an article supporting portion and an overhead conveyor portion above said supporting por. tion and the station; article stop means disposed in said supporting portion; trap members in said station pivotally mounted for movement into and out of article supporting position; lever means connected to said trap members; release means for said stop means including an element carried by the overhead conveyor portion and a cooperable member connected to said stop means; and means carried by said overhead conveyor including an article engaging member for advancing an article into the station and a project ing element cooperable with said lever means for moving said trap members into article release position.

7. In apparatus for stacking articles which includes an elevator, an article delivery station at the head of said elevator including trap mechanism for receiving an article and releasing it onto said elevator to form a stack of superimposed articles, and feed conveyor means including an overhead conveyor for advancing articles seriatim into said station: the improved trap mechanism which comprises members mounted at opposite sides of said station and adapted and arranged for horizontal pivotal movement about vertical axes between an extended position in which they project inwardly from opposite sides of said station. in which position they are capable of supporting an article delivered to said station, and a retracted position disposed closely adjacent the sides of said station, in which position they are incapable of supporting such ar-.

ticle, resilient means urging said members into article-supporting position, and lever means operated by engagement with said overhead conveyor for effecting intermittent pivotal movement of said members simultaneously to their retracted positions upon delivery of an article to said station.

8. Article stacking apparatus as defined in claim '7 in which said lever means for efiecting pivotal movement of said box-supporting members comprises a lever interconnecting said supporting members for effecting simultaneous piv otal movement thereof, a crank connected at one of its ends to said lever means and provided at its opposite end with a projecting pin, and spaced means carried by the conveyor means for intermittent contact with said pin during travel in said overhead conveyor.

ALVIN LENHERT ESHELMAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,488,431 Kukulj Mar, 25, 1924 1,601,971 Knapp Oct. 5, 1926 1,623,357 Moores Apr, 5, 1927 2,065,674 Fay Dec. 29, 1936 2,113,926 Pierce Apr. 12, 1988 2,315,003 Martin et al. Mar. 30, 1943. 

